DESCRIPTION (Applicant's Abstract): The time period following an acute bout of exercise is characterized by a greatly enhanced rate of glucose uptake and glycogen synthesis in skeletal muscle that may persist for several hours. The vast majority of glucose that is taken up by skeletal muscle is incorporated into glycogen, but little is known about the cellular signaling mechanisms that regulate this process. Therefore, the overall objective of my research project is to determine the molecular signaling mechanisms that regulate exercise-induced glycogen synthesis. Specifically, experiments are designed to study the roles of the muscle-specific, glycogen- and sarcoplasmic reticulum-associated protein phosphatase (PP 1 G) and the AMP-activated protein kinase (AMPK) in the regulation of glycogen synthesis following exercise, and the site-specific dephosphorylation of glycogen synthase that is associated with activation of the enzyme with muscle contractions. These studies will provide valuable information towards understanding the molecular basis of skeletal muscle glycogen metabolism. More importantly, this information may also be applied in the future towards understanding and treating the metabolic defects that are characteristic of chronic diseases such as type diabetes.